Synaptic alterations as a neurodevelopmental trait of Duchenne muscular dystrophy.

Dystrophinopaties, e.g., Duchenne muscular dystrophy (DMD), Becker muscular dystrophy and X-linked dilated cardiomyopathy are inherited neuromuscular diseases, characterized by progressive muscular degeneration, which however associate with a significant impact on general system physiology. The more severe is the pathology and its diversified manifestations, the heavier are its effects on organs, systems, and tissues other than muscles (skeletal, cardiac and smooth muscles). All dystrophinopaties are characterized by mutations in a single gene located on the X chromosome encoding dystrophin (Dp427) and its shorter isoforms, but DMD is the most devasting: muscular degenerations manifests within the first 4 years of life, progressively affecting motility and other muscular functions, and leads to a fatal outcome between the 20s and 40s. To date, after years of studies on both DMD patients and animal models of the disease, it has been clearly demonstrated that a significant percentage of DMD patients are also afflicted by cognitive, neurological, and autonomic disorders, of varying degree of severity. The anatomical correlates underlying neural functional damages are established during embryonic development and the early stages of postnatal life, when brain circuits, sensory and motor connections are still maturing. The impact of the absence of Dp427 on the development, differentiation, and consolidation of specific cerebral circuits (hippocampus, cerebellum, prefrontal cortex, amygdala) is significant, and amplified by the frequent lack of one or more of its lower molecular mass isoforms. The most relevant aspect, which characterizes DMD-associated neurological disorders, is based on morpho-functional alterations of selective synaptic connections within the affected brain areas. This pathological feature correlates neurological conditions of DMD to other severe neurological disorders, such as schizophrenia, epilepsy and autistic spectrum disorders, among others. This review discusses the organization and the role of the dystrophin-dystroglycan complex in muscles and neurons, focusing on the neurological aspect of DMD and on the most relevant morphological and functional synaptic alterations, in both central and autonomic nervous systems, described in the pathology and its animal models.

Cultured hippocampal neurons of dystrophic mdx mice respond differently from those of wild type mice to an acute treatment with corticosterone.

Duchenne muscular dystrophy is a lethal genetic disease characterised by progressive degeneration of skeletal muscles induced by deficiency of dystrophin, a cytoskeletal protein expressed in myocytes and in certain neuron populations. The severity of the neurological disorder varies in humans and animal models owing to dysfunction in numerous brain areas, including the hippocampus. Cyclic treatments with high-dose glucocorticoids remain a major pharmacological approach for treating the disease; however, elevated systemic levels of either stress-induced or exogenously administered anti-inflammatory molecules dramatically affect hippocampal activity. In this study, we analysed and compared the response of hippocampal neurons isolated from wild-type and dystrophic mdx mice to acute administration of corticosterone in vitro, without the influence of other glucocorticoid-regulated processes. Our results showed that in neurons of mdx mice, both the genomic and intracellular signalling-mediated responses to corticosterone were affected compared to those in wild-type animals, evoking the characteristic response to detrimental chronic glucocorticoid exposure. Responsiveness to glucocorticoids is, therefore, another function of hippocampal neurons possibly affected by deficiency of Dp427 since embryonic development. Knowing the pivotal role of hippocampus in stress hormone signalling, attention should be paid to the effects that prolonged glucocorticoid treatments may have on this and other brain areas of DMD patients.

Prenatal expression of D-aspartate oxidase causes early cerebral D-aspartate depletion and influences brain morphology and cognitive functions at adulthood.

The free D-amino acid, D-aspartate, is abundant in the embryonic brain but significantly decreases after birth. Besides its intracellular occurrence, D-aspartate is also present at extracellular level and acts as an endogenous agonist for NMDA and mGlu5 receptors. These findings suggest that D-aspartate is a candidate signaling molecule involved in neural development, influencing brain morphology and behaviors at adulthood. To address this issue, we generated a knockin mouse model in which the enzyme regulating D-aspartate catabolism, D-aspartate oxidase (DDO), is expressed starting from the zygotic stage, to enable the removal of D-aspartate in prenatal and postnatal life. In line with our strategy, we found a severe depletion of cerebral D-aspartate levels (up to 95%), since the early stages of mouse prenatal life. Despite the loss of D-aspartate content, Ddo knockin mice are viable, fertile, and show normal gross brain morphology at adulthood. Interestingly, early D-aspartate depletion is associated with a selective increase in the number of parvalbumin-positive interneurons in the prefrontal cortex and also with improved memory performance in Ddo knockin mice. In conclusion, the present data indicate for the first time a biological significance of precocious D-aspartate in regulating mouse brain formation and function at adulthood.

Electroacupuncture in rats normalizes the diabetes-induced alterations in the septo-hippocampal cholinergic system.

Diabetes induces early sufferance in the cholinergic septo-hippocampal system, characterized by deficits in learning and memory, reduced hippocampal plasticity and abnormal pro-nerve growth factor (proNGF) release from hippocampal cells, all linked to dysfunctions in the muscarinic cholinergic modulation of hippocampal physiology. These alterations are associated with dysregulation of several cholinergic markers, such as the NGF receptor system and the acetylcholine biosynthetic enzyme choline-acetyl transferase (ChAT), in the medial septum and its target, the hippocampus. Controlled and repeated sensory stimulation by electroacupuncture has been proven effective in counteracting the consequences of diabetes on cholinergic system physiology in the brain. Here, we used a well-established Type 1 diabetes model, obtained by injecting young adult male rats with streptozotocin, to induce sufferance in the septo-hippocampal system. We then evaluated the effects of a 3-week treatment with low-frequency electroacupuncture on: (a) the expression and protein distribution of proNGF in the hippocampus, (b) the tissue distribution and content of NGF receptors in the medial septum, (c) the neuronal cholinergic and glial phenotype in the septo-hippocampal circuitry. Twice-a-week treatment with low-frequency electroacupuncture normalized, in both hippocampus and medial septum, the ratio between the neurotrophic NGF and its neurotoxic counterpart, the precursor proNGF. Electroacupuncture regulated the balance between the two major proNGF variants (proNGF-A and proNGF-B) at both gene expression and protein synthesis levels. In addition, electroacupuncture recovered to basal level the pro-neurotrophic NGF receptor tropomyosin receptor kinase-A content, down-regulated in medial septum cholinergic neurons by diabetes. Electroacupuncture also regulated ChAT content in medial septum neurons and its anterograde transport toward the hippocampus. Our data indicate that repeated sensory stimulation can positively affect brain circuits involved in learning and memory, reverting early impairment induced by diabetes development. Electroacupuncture could exert its effects on the septo-hippocampal cholinergic neurotransmission in diabetic rats, not only by rescuing the hippocampal muscarinic responsivity, as previously described, but also normalizing acetylcholine biosynthesis and NGF metabolism in the hippocampus.

Shortened primary cilium length and dysregulated Sonic hedgehog signaling in Niemann-Pick C1 disease.

The Niemann-Pick type C1 (NPC1) disease is a neurodegenerative lysosomal storage disorder due to mutations in the NPC1 gene, encoding a transmembrane protein related to the Sonic hedgehog (Shh) receptor, Patched, and involved in intracellular trafficking of cholesterol. We have recently found that the proliferation of cerebellar granule neuron precursors is significantly reduced in Npc1-/- mice due to the downregulation of Shh expression. This finding prompted us to analyze the formation of the primary cilium, a non-motile organelle that is specialized for Shh signal transduction and responsible, when defective, for several human genetic disorders. In this study, we show that the expression and subcellular localization of Shh effectors and ciliary proteins are severely disturbed in Npc1-deficient mice. The dysregulation of Shh signaling is associated with a shortening of the primary cilium length and with a reduction of the fraction of ciliated cells in Npc1-deficient mouse brains and the human fibroblasts of NPC1 patients. These defects are prevented by treatment with 2-hydroxypropyl-ß-cyclodextrin, a promising therapy currently under clinical investigation. Our findings indicate that defective Shh signaling is responsible for abnormal morphogenesis of the cerebellum of Npc1-deficient mice and show, for the first time, that the formation of the primary cilium is altered in NPC1 disease.

NGF-dependent axon growth and regeneration are altered in sympathetic neurons of dystrophic mdx mice.

Duchenne muscular dystrophy (DMD) is a lethal disease, determined by lack of dystrophin (Dp427), a muscular cytoskeletal protein also expressed by selected neuronal populations. Consequently, besides muscular wasting, both human patients and DMD animal models suffer several neural disorders. In previous studies on the superior cervical ganglion (SCG) of wild type and dystrophic mdx mice (Lombardi et al. 2008), we hypothesized that Dp427 could play some role in NGF-dependent axonal growth, both during development and adulthood. To address this issue, we first analyzed axon regeneration potentials of SCG neurons of both genotypes after axotomy in vivo. While noradrenergic innervation of mdx mouse submandibular gland, main source of nerve growth factor (NGF), recovered similarly to wild type, iris innervation (muscular target) never did. We, therefore, evaluated whether dystrophic SCG neurons were poorly responsive to NGF, especially at low concentration. Following in vitro axotomy in the presence of either 10 or 50ng/ml NGF, the number of regenerated axons in mdx mouse neuron cultures was indeed reduced, compared to wild type, at the lower concentration. Neurite growth parameters (i.e. number, length), growth cone dynamics and NGF/TrkA receptor signaling in differentiating neurons (not injured) were also significantly reduced when cultured with 10ng/ml NGF, but also with higher NGF concentrations. In conclusion, we propose a role for Dp427 in NGF-dependent cytoskeletal dynamics associated to growth cone advancement, possibly through indirect stabilization of TrkA receptors. Considering NGF activity in nervous system development/remodeling, this aspect could concur in some of the described DMD-associated neural dysfunctions.

Autoregulation of the Kluyveromyces lactis pyruvate decarboxylase gene KlPDC1 involves the regulatory gene RAG3.

In the yeast Kluyveromyces lactis, the pyruvate decarboxylase gene KlPDC1 is strongly regulated at the transcription level by different environmental factors. Sugars and hypoxia act as inducers of transcription, while ethanol acts as a repressor. Their effects are mediated by gene products, some of which have been characterized. KlPDC1 transcription is also strongly repressed by its product--KlPdc1--through a mechanism called autoregulation. We performed a genetic screen that allowed us to select and identify the regulatory gene RAG3 as a major factor in the transcriptional activity of the KlPDC1 promoter in the absence of the KlPdc1 protein, i.e. in the autoregulatory mechanism. We also showed that the two proteins Rag3 and KlPdc1 interact, co-localize in the cell and that KlPdc1 may control Rag3 nuclear localization.

Ventral striatal plasticity and spatial memory.

Spatial memory formation is a dynamic process requiring a series of cellular and molecular steps, such as gene expression and protein translation, leading to morphological changes that have been envisaged as the structural bases for the engram. Despite the role suggested for medial temporal lobe plasticity in spatial memory, recent behavioral observations implicate specific components of the striatal complex in spatial information processing. However, the potential occurrence of neural plasticity within this structure after spatial learning has never been investigated. In this study we demonstrate that blockade of cAMP response element binding protein-induced transcription or inhibition of protein synthesis or extracellular proteolytic activity in the ventral striatum impairs long-term spatial memory. These findings demonstrate that, in the ventral striatum, similarly to what happens in the hippocampus, several key molecular events crucial for the expression of neural plasticity are required in the early stages of spatial memory formation.

α7 Nicotinic Acetylcholine Receptors May Improve Schwann Cell Regenerating Potential via Metabotropic Signaling Pathways.

BACKGROUND: Schwann cells (SCs) are glial cells involved in peripheral axon myelination. SCs also play a strategic role after peripheral nerve injury, regulating local inflammation and axon regeneration. Our previous studies demonstrated the presence of cholinergic receptors in SCs. In particular, the α7 nicotinic acetylcholine receptors (nAChRs) are expressed in SCs after peripheral axotomy, suggesting their involvement in the regulation of SC-regenerating properties. To clarify the role that α7 nAChRs may play after peripheral axon damage, in this study we investigated the signal transduction pathways triggered by receptor activation and the effects produced by their activation. METHODS: Both ionotropic and metabotropic cholinergic signaling were analyzed by calcium imaging and Western blot analysis, respectively, following α7 nAChR activation. In addition, the expression of c-Jun and α7 nAChRs was evaluated by immunocytochemistry and Western blot analysis. Finally, the cell migration was studied by a wound healing assay. RESULTS: Activation of α7 nAChRs, activated by the selective partial agonist ICH3, did not induce calcium mobilization but positively modulated the PI3K/AKT/mTORC1 axis. Activation of the mTORC1 complex was also supported by the up-regulated expression of its specific p-p70 S6KThr389 target. Moreover, up-regulation of p-AMPKThr172, a negative regulator of myelination, was also observed concomitantly to an increased nuclear accumulation of the transcription factor c-Jun. Cell migration and morphology analyses proved that α7 nAChR activation also promotes SC migration. CONCLUSIONS: Our data demonstrate that α7 nAChRs, expressed by SCs only after peripheral axon damage and/or in an inflammatory microenvironment, contribute to improve the SCs regenerating properties. Indeed, α7 nAChR stimulation leads to an upregulation of c-Jun expression and promotes Schwann cell migration by non-canonical pathways involving the mTORC1 activity.

Microglia reactivity entails microtubule remodeling from acentrosomal to centrosomal arrays.

Microglia reactivity entails a large-scale remodeling of cellular geometry, but the behavior of the microtubule cytoskeleton during these changes remains unexplored. Here we show that activated microglia provide an example of microtubule reorganization from a non-centrosomal array of parallel and stable microtubules to a radial array of more dynamic microtubules. While in the homeostatic state, microglia nucleate microtubules at Golgi outposts, and activating signaling induces recruitment of nucleating material nearby the centrosome, a process inhibited by microtubule stabilization. Our results demonstrate that a hallmark of microglia reactivity is a striking remodeling of the microtubule cytoskeleton and suggest that while pericentrosomal microtubule nucleation may serve as a distinct marker of microglia activation, inhibition of microtubule dynamics may provide a different strategy to reduce microglia reactivity in inflammatory disease.

Lack of dystrophin in mdx mice modulates the expression of genes involved in neuron survival and differentiation.

Duchenne muscular dystrophy is an X-linked disease characterized by progressive and lethal muscular wasting. Dystrophic patients, however, are also afflicted by several neurological disorders, the importance of which is generally underestimated. As promising therapies for muscles are currently in clinical trial stages, with the potential to provide an increase in the lifespan of young patients, determination of the genetic and molecular aspects characterizing this complex disease is crucial in order to allow the development of therapeutic approaches specifically designed for the nervous system. In this study, differences in gene expression in the superior cervical ganglion of postnatal day (P)5, P10 and 6-7-week-old wild-type and genetically dystrophic mdx mice were evaluated by DNA microarray analysis. The main aim was to verify whether the lack of dystrophin affected the transcript levels of genes related to different aspects of neuron development and differentiation. Ontological analysis of more than 500 modulated genes showed significant differences in genetic class enrichment at each postnatal date. Upregulated genes mainly fell in the categories of vesicular trafficking, and cytoskeletal and synaptic organization, whereas downregulated genes were associated with axon development, growth factors, intracellular signal transduction, metabolic processes, gene expression regulation, synapse morphogenesis, and nicotinic receptor clustering. These data strongly suggest that the structural and functional alterations previously described in both the autonomic and central nervous systems of mdx mice with respect to wild-type mice and related to crucial aspects of neuron life (i.e. postnatal development, differentiation, and plasticity) result not only from protein post-translational modifications, but also from direct and/or indirect modulation of gene expression.

Muscle Damage in Dystrophic mdx Mice Is Influenced by the Activity of Ca2+-Activated KCa3.1 Channels.

Duchenne muscular dystrophy (DMD) is an X-linked disease, caused by a mutant dystrophin gene, leading to muscle membrane instability, followed by muscle inflammation, infiltration of pro-inflammatory macrophages and fibrosis. The calcium-activated potassium channel type 3.1 (KCa3.1) plays key roles in controlling both macrophage phenotype and fibroblast proliferation, two critical contributors to muscle damage. In this work, we demonstrate that pharmacological blockade of the channel in the mdx mouse model during the early degenerative phase favors the acquisition of an anti-inflammatory phenotype by tissue macrophages and reduces collagen deposition in muscles, with a concomitant reduction of muscle damage. As already observed with other treatments, no improvement in muscle performance was observed in vivo. In conclusion, this work supports the idea that KCa3.1 channels play a contributing role in controlling damage-causing cells in DMD. A more complete understanding of their function could lead to the identification of novel therapeutic approaches.

Lack of dystrophin functionally affects α3ß2/ß4-nicotinic acethylcholine receptors in sympathetic neurons of dystrophic mdx mice.

In the sympathetic superior cervical ganglion (SCG), nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission. We previously demonstrated that in SCG neurons of mdx mice, an animal model for Duchenne muscular dystrophy, lack of dystrophin causes a decrease, compared to the wild-type, in post-synaptic nAChRs containing the α3 subunit associated with ß2 and/or ß4 (α3ß2/ß4-nAChRs), but not in those containing the α7 subunit. Here we show, by whole cell patch-clamp recordings from cultured SCG neurons, that both nicotine and acetylcholine-evoked currents through α3ß2/ß4-nAChRs are significantly reduced in mdx mice compared to the wild-type, while those through α7-nAChR are unaffected. This reduction associates with that of protein levels of α3, ß2 and ß4 subunits. Therefore, we suggest that, in mdx mouse SCG neurons, lack of dystrophin, by specifically affecting membrane stabilization of α3ß2/ß4-nAChRs, could determine an increase in receptor internalization and degradation, with consequent reduction in the fast intraganglionic cholinergic transmission.

Dystrophin Is Required for the Proper Timing in Retinal Histogenesis: A Thorough Investigation on the mdx Mouse Model of Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal X-linked muscular disease caused by defective expression of the cytoskeletal protein dystrophin (Dp427). Selected autonomic and central neurons, including retinal neurons, express Dp427 and/or dystrophin shorter isoforms. Because of this, DMD patients may also experience different forms of cognitive impairment, neurological and autonomic disorders, and specific visual defects. DMD-related damages to the nervous system are established during development, suggesting a role for all dystrophin isoforms in neural circuit development and differentiation; however, to date, their function in retinogenesis has never been investigated. In this large-scale study, we analyzed whether the lack of Dp427 affects late retinogenesis in the mdx mouse, the most well studied animal model of DMD. Retinal gene expression and layer maturation, as well as neural cell proliferation, apoptosis, and differentiation, were evaluated in E18 and/or P0, P5, P10, and adult mice. In mdx mice, expression of Capn3, Id3 (E18-P5), and Dtnb (P5) genes, encoding proteins involved in different aspects of retina development and synaptogenesis (e.g., Calpain 3, DNA-binding protein inhibitor-3, and ß-dystrobrevin, respectively), was transiently reduced compared to age-matched wild type mice. Concomitantly, a difference in the time required for the retinal ganglion cell layer to reach appropriate thickness was observed (P0-P5). Immunolabeling for specific cell markers also evidenced a significant dysregulation in the number of GABAergic amacrine cells (P5-P10), a transient decrease in the area immunopositive for the Vesicular Glutamate Transporter 1 (VGluT1) during ribbon synapse maturation (P10) and a reduction in the number of calretinin+ retinal ganglion cells (RGCs) (adults). Finally, the number of proliferating retinal progenitor cells (P5-P10) and apoptotic cells (P10) was reduced. These results support the hypothesis of a role for Dp427 during late retinogenesis different from those proposed in consolidated neural circuits. In particular, Dp427 may be involved in shaping specific steps of retina differentiation. Notably, although most of the above described quantitative alterations recover over time, the number of calretinin+ RGCs is reduced only in the mature retina. This suggests that alterations subtler than the timing of retinal maturation may occur, a hypothesis that demands further in-depth functional studies.

Dystroglycan Mediates Clustering of Essential GABAergic Components in Cerebellar Purkinje Cells.

Muscle dystrophin-glycoprotein complex (DGC) links the intracellular cytoskeleton to the extracellular matrix. In neurons, dystroglycan and dystrophin, two major components of the DGC, localize in a subset of GABAergic synapses, where their function is unclear. Here we used mouse models to analyze the specific role of the DGC in the organization and function of inhibitory synapses. Loss of full-length dystrophin in mdx mice resulted in a selective depletion of the transmembrane ß-dystroglycan isoform from inhibitory post-synaptic sites in cerebellar Purkinje cells. Remarkably, there were no differences in the synaptic distribution of the extracellular α-dystroglycan subunit, of GABAA receptors and neuroligin 2. In contrast, conditional deletion of the dystroglycan gene from Purkinje cells caused a disruption of the DGC and severely impaired post-synaptic clustering of neuroligin 2, GABAA receptors and scaffolding proteins. Accordingly, whole-cell patch-clamp analysis revealed a significant reduction in the frequency and amplitude of spontaneous IPSCs recorded from Purkinje cells. In the long-term, deletion of dystroglycan resulted in a significant decrease of GABAergic innervation of Purkinje cells and caused an impairment of motor learning functions. These results show that dystroglycan is an essential synaptic organizer at GABAergic synapses in Purkinje cells.

Effects of intranasally-delivered pro-nerve growth factors on the septo-hippocampal system in healthy and diabetic rats.

Pro-nerve growth factor (proNGF) is the predominant form of NGF in the brain and its levels increase in neurodegenerative diseases. The balance between NGF receptors may explain the contradictory biological activities of proNGF. However, the specific role of the two main proNGF variants is mostly unexplored. proNGF-A is prevalently expressed in healthy brain, while proNGF-B content increases in the neuro-degenerating brain. Recently we have investigated in vitro the biological action of native mouse proNGF variants. To gain further insights into the specific functions of the two proNGFs, here we intranasally delivered mouse-derived proNGF-A and proNGF-B to the brain parenchyma of healthy and diabetic rats, the latter characterized by dysfunction in spatial learning and memory, in the septo-hippocampal circuitry and by relative increase in proNGF-B hippocampal levels. Exogenous proNGF-B induces depression of hippocampal DG-LTP and impairment of hippocampal neurogenesis in healthy animals, with concomitant decrease in basal forebrain cholinergic neurons and cholinergic fibers projecting to the hippocampus. proNGF-A, while ineffective in healthy animals, rescues the diabetes-induced impairment in DG-LTP and hippocampal neurogenesis, promoting the concomitant recovery of the basal forebrain cholinergic phenotype. Our experimental evidences suggest that the balance between different proNGFs may influence the development and progression of neurodegenerative diseases.

Octodon degus: a natural model of multimorbidity for ageing research.

Integrating the multifactorial processes co-occurring in both physiological and pathological human conditions still remains one of the main challenges in translational investigation. Moreover, the impact of age-associated disorders has increased, which underlines the urgent need to find a feasible model that could help in the development of successful therapies. In this sense, the Octodon degus has been indicated as a 'natural' model in many biomedical areas, especially in ageing. This rodent shows complex social interactions and high sensitiveness to early-stressful events, which have been used to investigate neurodevelopmental processes. Interestingly, a high genetic similarity with some key proteins implicated in human diseases, such as apolipoprotein-E, ß-amyloid or insulin, has been demonstrated. On the other hand, the fact that this animal is diurnal has provided important contribution in the field of circadian biology. Concerning age-related diseases, this rodent could be a good model of multimorbidity since it naturally develops cognitive decline, neurodegenerative histopathological hallmarks, visual degeneration, type II diabetes, endocrinological and metabolic dysfunctions, neoplasias and kidneys alterations. In this review we have collected and summarized the studies performed on the Octodon degus through the years that support its use as a model for biomedical research, with a special focus on ageing.

Intracellular bacteriolysis triggers a massive apoptotic cell death in Shigella-infected epithelial cells.

Infected epithelial cells, which act as a first barrier against pathogens, seldom undergo apoptosis. Rather, infected epithelial cells undergo a slow cell death that displays hallmarks of necrosis. Here, we demonstrate that rapid intracellular lysis of Shigella flexneri, provoked by either the use of a diaminopimelic acid auxotroph mutant or treatment of infected cells with antibiotics of the beta-lactam family, resulted in a massive and rapid induction of apoptotic cell death. This intracellular bacteriolysis-mediated apoptotic death (IBAD) was characterized by the specific involvement of the mitochondrial-dependent cytochrome c/Apaf-1 axis that resulted in the activation of caspases-3, -6 and -9. Importantly, Bcl-2 family members and the NF-kappaB pathway seemed to be critical modulators of IBAD. Finally, we identified that IBAD was also triggered by Salmonella enterica serovar Typhimurium but not by the Gram-positive bacteria, Listeria monocytogenes. Together, our results demonstrate that, contrary to previous findings, epithelial cells are intrinsically able to mount an efficient apoptotic cell death response following infection. Indeed, apoptosis in normal circumstances is masked by powerful anti-apoptotic mechanisms, which are overcome in IBAD. Our results also uncover an unexpected consequence of the treatment of infected cells with certain classes of antibiotics.

The multifaceted role of metalloproteinases in physiological and pathological conditions in embryonic and adult brains.

Matrix metalloproteinases (MMPs) are a large family of ubiquitous extracellular endopeptidases, which play important roles in a variety of physiological and pathological conditions, from the embryonic stages throughout adult life. Their extraordinary physiological "success" is due to concomitant broad substrate specificities and strict regulation of their expression, activation and inhibition levels. In recent years, MMPs have gained increasing attention as significant effectors in various aspects of central nervous system (CNS) physiology. Most importantly, they have been recognized as main players in a variety of brain disorders having different etiologies and evolution. A common aspect of these pathologies is the development of acute or chronic neuroinflammation. MMPs play an integral part in determining the result of neuroinflammation, in some cases turning its beneficial outcome into a harmful one. This review summarizes the most relevant studies concerning the physiology of MMPs, highlighting their involvement in both the developing and mature CNS, in long-lasting and acute brain diseases and, finally, in nervous system repair. Recently, a concerted effort has been made in identifying therapeutic strategies for major brain diseases by targeting MMP activities. However, from this revision of the literature appears clear that MMPs have multifaceted functional characteristics, which modulate physiological processes in multiple ways and with multiple consequences. Therefore, when choosing MMPs as possible targets, great care must be taken to evaluate the delicate balance between their activation and inhibition and to determine at which stage of the disease and at what level they become active in order maximize chances of success.

Recovery of hippocampal functions and modulation of muscarinic response by electroacupuncture in young diabetic rats.

The muscarinic receptor response to acetylcholine regulates the hippocampal-related learning, memory, neural plasticity and the production and processing of the pro-nerve growth factor (proNGF) by hippocampal cells. The development and progression of diabetes generate a mild cognitive impairment reducing the functions of the septo-hippocampal cholinergic circuitry, depressing neural plasticity and inducing proNGF accumulation in the brain. Here we demonstrate, in a rat model of early type-1 diabetes, that a physical therapy, the electroacupuncture, counteracts the diabetes-induced deleterious effects on hippocampal physiology by ameliorating hippocampal-related memory functions; recovering the impaired long-term potentiation at the dentate gyrus (DG-LTP) and the lowered expression of the vesicular glutamate transporter 1; normalizing the activity-dependent release of proNGF in diabetic rat hippocampus. Electroacupuncture exerted its therapeutic effects by regulating the expression and activity of M1- and M2-acetylcholine muscarinic receptors subtypes in the dentate gyrus of hippocampus. Our results suggest that a physical therapy based on repetitive sensory stimulation could promote hippocampal neural activity, neuronal metabolism and functions, and conceivably improve the diabetes-induced cognitive impairment. Our data can support the setup of therapeutic protocols based on a better integration between physical therapies and pharmacology for the cure of diabetes-associated neurodegeneration and possibly for Alzheimer's disease.